17Frank13
Member
I am currently undertaking a distance learning course to become a Domestic Installer. I have a domestic installation where the meter is more than 3m. from the CU.Because of this the supplier will not allow the tails between meter and CU to be protected by their 60A. fuse. I have had to have installed a double pole isolation switch, having an 80A. fuse, next to the meter and a small CU next to the switch with an RCD to protect the tails between the new CU and the main CU. All tails are in 25 sq. mm. cable. The RCD in the new CU next to the meter is a Proteus type AC, 80A., 230V., RATED @ 0.03A, housed in a Marlanvil 92.04 CU. Recently pressed the test button on this RCD and nothing happened, so I tried again, this tim keeping the test button depressed. There was an alarming bang, but again, the RCD did not trip. It therefore appears the RCD is faulty and needs to be replaced. I understand, however that as this RCD is in series with other RCD's in the main CU, it should have a timer delay and thus be an 'S' type RCD. It appears that I cannot get a 30mA RCD as an S type and can only get a 100mA RCD, which, I understand, will not protect against shock, only fire. Can anyone advise me as to which RCD I should replace the faulty on with? I have asked my tutors and other electricians, but no-one seems to know. Some advice on this would be much appreciated.